Compact gamma camera

ABSTRACT

A gamma camera system comprising: a pair of gamma camera heads; and a stand on which the gamma camera heads are mounted, wherein the camera system is configurable in one of at least two configurations, including: an operational condition in which faces of the gamma camera heads form an angle of between 80 and 100 degrees; and a non-operational parking configuration in which a front face of the gamma camera heads form an angle substantially greater than 100 degrees.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.10/802,404 filed Mar. 16, 2004, the contents of which are incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention relates to gamma camera systems, and moreparticularly to a gamma camera with a dual detector camera head.

BACKGROUND OF THE INVENTION

Gamma camera systems are used in nuclear medicine to produce an imagebased on the internal physiology of a patient. In the process ofexamination, a radio-pharmaceutical is introduced into the patient. Thesubstance migrates to certain organs of the patients body. Measuringradiation emitted from the patient can be used to image the distributionof the radio-pharmaceutical in the patient. PCT Publication WO 98/27443,the disclosure of which is incorporated herein by reference, describes alight weight gamma camera and details relating to performing suchmeasurements.

In order to supply a tomographic image of a patient, it is commonpractice to measure the radiation with a machine controlled gamma cameraperforming a contour trajectory of the patient. Such a process requiresmoving the gamma camera with precise positioning around the patient inorder to construct an accurate tomographic image. U.S. Pat. No.4,649,277 to Terra et al., the disclosure of which is incorporatedherein by reference, describes a gamma camera mounted on a gantrysupported by a column running on guides. By positioning the patient in aselected position and rotating the gamma camera around the axis of thepatient, a tomographic image is formed.

In order to improve sensitivity and speed up the process of forming atomographic image it has been suggested using two cameras rotating aboutthe axis of the patient. U.S. Pat. No. 5,594,251 to Fleury et al., thedisclosure of which is incorporated herein by reference, describes asystem with a fixed base and two gamma cameras rotating about abarycentric axis.

In U.S. Pat. No. 5,811,813 to Maor, the disclosure of which isincorporated herein by reference, there is described a gamma camera headwith two detectors forming an angle between them. A dual detector gammacamera head allows quicker and more accurate measurements by sensingradiation at two angles at the same time. This is useful for spotmeasurements using a non moving camera. Additionally, in tomographicimages a dual detector head enables measuring a larger arc with lessrotation, for example a 180° arc with a 90° rotation.

SUMMARY OF THE INVENTION

An aspect of some embodiments of the invention relates to a gamma camerasystem with a dual headed gamma camera mounted on an arm and including arotation mechanism comprising a pivot mounted on the arm, allowing forrotation of the gamma camera heads with respect to the arm about a lineparallel to the connection.

In an exemplary embodiment of the invention, the gamma camera useslinear motion in conjunction with rotation of the gamma camera headsaround an axis other than the patient axis to provide multiple views ofthe patient. Using linear motion to acquire the image optionally reducesthe footprint of the system compared to a system that surrounds thepatient.

In some embodiments of the invention, the detection path of the camerais selected by the gamma camera system before beginning the scan.Alternatively or additionally, the detection path varies based on thecontour of the patient as detected while scanning.

An aspect of some embodiments of the invention relates to a gamma camerasystem having two gamma camera heads joined at substantially a rightangle, and adapted to provide linear motion of the heads in a planecontaining the right angle.

An aspect of some embodiments of the invention relates to a gamma camerasystem for reconstructing the distribution of gamma sources in a threedimensional volume having an axis corresponding to an axis about whichviews of the volume are taken by one or more gamma camera heads of thevolume, the system including at least one head having a dimensionsmaller than a largest dimension of the reconstruction volumeperpendicular to the axis.

In some embodiments of the invention, various patient positions can beused, for example lying down, standing up or sitting.

There is thus provided according to an exemplary embodiment of theinvention, a gamma camera system comprising:

a pair of gamma camera heads connected to form substantially a rightangle;

an arm on which the pair of cameras heads are mounted; and

a rotation mechanism comprising a pivot mounted on the arm, allowing forrotation of the gamma camera heads with respect to the arm about a lineparallel to the connection.

In an embodiment of the invention, the gamma camera system is adapted toallow linear movement of the gamma camera heads in at least onedirection perpendicular to the line. Optionally, the linear motion isprovided without moving a base on which the gamma camera system ismounted.

In an embodiment of the invention, the gamma camera system is adapted toallow linear motion of the gamma camera heads in all directionsperpendicular to the line.

In an embodiment of the invention, the gamma camera system is adapted toperform at least a partial rotation of the gamma camera heads about anobject within a quadrant formed by the heads, by combination of linearmotion and rotation about the pivot. In various embodiments of theinvention, the partial rotation is at least 90° or at least 180°.

In an embodiment of the invention, the arm is adapted to rotate thecamera heads such that the line is rotatable about an axis perpendicularto the line.

Optionally, the arm comprises between 2 to 6 extensions, which extendtelescopically.

Optionally, the gamma camera heads comprise sensors that sense obstaclesin a path followed by the camera, in order to prevent the camera fromcolliding with a scanned object.

Optionally, the camera automatically follows a path which is a contourof a scanned object. Optionally, the camera follows a preselected path.Optionally, the heads follows a path that is chosen during motion of theheads about the object. Optionally, the gamma camera system is adaptedto scan a prone patient. Alternatively or additionally, it is adapted toscan a standing patient. Alternatively or additionally, it is adapted toscan a seated patient.

In an embodiment of the invention, the gamma camera is adapted toacquire radiation data from all directions of a scanned object.Alternatively or additionally, the gamma camera is adapted to acquiredata from 180° about the scanned object.

Optionally, the gamma camera is adapted to perform a scan of the entirelength of a patient, without moving the patient.

Optionally the gamma camera includes a controller adapted to reconstructimages within a reconstruction circle and wherein the dimension of eachof the gamma camera heads in a plane perpendicular to the line is atleast as large as the diameter of the circle.

In an embodiment of the invention, the gamma camera is operative toreconstruct images within a reconstruction circle and wherein thedimension of each of the gamma camera heads in a plane perpendicular tothe line is at least as large as the radius of the circle, but smallerthan the diameter of the circle. Optionaly, the dimension is less than1.5 times the radius.

Optionally, the heads are rigidly connected at the angle.

There is further provided, in accordance with an embodiment of theinvention, a gamma camera system comprising:

a pair of gamma camera heads connected to form substantially a rightangle; and

an arm on which the pair of cameras heads are mounted;

wherein the arm is adapted to allow for linear motion of the pair ofcamera heads in a plane containing the right angle.

Optionally, the arm is adapted to move in the plane without moving abase on which the camera system is mounted.

Optionally, the arm is adapted to allow for linear motion in alldirections within the plane of the right angle.

Optionally, the gamma camera includes a controller operative toreconstruct images within a reconstruction circle and wherein the amountof the linear motion is at least as large as a diameter of the circle.

Optionally, the heads are rigidly connected at the angle.

There is further provided, in accordance with an embodiment of theinvention, a gamma camera system comprising:

a pair of gamma camera heads connected to form an angle and adapted toview a reconstruction volume from a plurality of directions having anaxis perpendicular to a plane containing the right angle; and

a controller adapted to reconstruct a three dimensional image ofradiation sources in the reconstruction volume from data acquired by thecamera heads as they rotate about the axis,

wherein each of the pair of gamma camera heads has a dimension in theplane containing the angle smaller than a largest dimension of thereconstruction volume perpendicular to the axis.

In an embodiment of the invention, the angle is substantially equal to aright angle.

In an embodiment of the invention, each of the gamma camera heads has adimension of between 50% and 75% of the largest dimension.

Optionally, the heads are rigidly connected at the angle.

BRIEF DESCRIPTION OF FIGURES

Particular exemplary embodiments of the invention will be described withreference to the following description of embodiments in conjunctionwith the figures, wherein identical structures, elements or parts whichappear in more than one figure are generally labeled with a same orsimilar number in all the figures in which they appear, in which:

FIG. 1 is a schematic illustration of a gamma camera system according toan exemplary embodiment of the invention;

FIGS. 2A, 2B, 2C, 2D, 2E and 2F are schematic illustrations of a gammacamera system, in various positions of use, according to an exemplaryembodiment of the invention;

FIGS. 3A, 3B, 3C, 3D and 3E are schematic illustrations of a gammacamera system, in various positions of use, according to an exemplaryembodiment of the invention; and

FIGS. 4A, 4B and 4C are schematic illustrations of a gamma camerasystem, in parking positions, according to an exemplary embodiment ofthe invention.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 is a schematic illustration of a gamma camera system 100according to an exemplary embodiment of the invention. System 100comprises an L shaped dual gamma camera head 170 and support apparatusto support head 170 and control its position in space. Cartesiancoordinate system 250 will be used to describe the directions of motionby the support apparatus supporting head 170. In this coordinate system,the z-axis is the axis of a prone patient, and is parallel to the floor.

As shown in FIG. 1, the support apparatus for head 170 is mounted on anextendible support arm 140. Extendible support arm 140, optionallycomprises between 2 to 6 parts which expand telescopically to allowextension of the support arm to a larger distance than the size of anarm base 130 which houses the expandable parts. Arm base 130 optionallyallows vertical motion along a column 120. Column 120 is held up by aheavy base 110 (for example filled with lead), which keeps system 100from falling over due to the moment of the head. Alternatively oradditionally base 110 is fastened to the floor. In some embodiments ofthe invention, base 110 is connected to a stabilization base (not shown)on the exterior side of the floor, for example on the ceiling of thefloor below, to support stabilizing column 120.

In an exemplary embodiment of the invention, system 100 can be used inrooms with limited space, since it is based on a small footprint anddoes not need to move around or form a large trajectory for head 170, asin other systems described above in the incorporated references.

In an exemplary embodiment of the invention, head 170 is connected toextendible support arm 140 with a rotatable joint 150, permittingrotation of head 170 in the XY plane of coordinate system 250. It isnoted that while head 170 rotates in the XY plane, as do heads in priorart gamma cameras, its axis of rotation is not centered in the patientor even in a tomographic reconstruction region. Rather, extendiblesupport arm 140 contributes translational motion along the X axis andarm base 130 optionally contributes translational motion along the Yaxis of coordinate system 250.

In the embodiment shown, the pivot is at the end of the line joining theheads. This allows for 360° rotation of the heads about the pivot axis.Alternatively, the pivot can be placed at the center of the line joiningthe heads. This would restrict the rotation of the heads to somewhatless than 360°. As can be readily understood from the followingexplanation, in general 360° rotation is not generally required. Centrallocation of pivot results in a more stable structure.

In an exemplary embodiment of the invention, the movement of the partsof the gamma camera support system are controlled by a standardhydraulic and/or electronic system. Optionally, a computerized control190 controls the movement and positioning of head 170. In someembodiments of the invention, a remote control is used, so an operatorcan control the system from a distance, for example from across theroom.

In some embodiments of the invention, head 170 is equipped with sensors160 that sense objects in the proximity of head 170, in order to guideits motion when examining a patient, for example to accurately traversethe contour of the patient without hitting the patient. Such sensors, invarious positions notify a motion control to alter movement of the heador pause its movement to overcome obstacles.

In an exemplary embodiment of the invention, a patient 180 is positionedon an examination bed 200 in order to be examined by system 100. In someembodiments of the invention examination bed 200 is accessible fromunderneath. As a result head 170 can pass under the examination bed inorder to acquire radiation events from patient 180, from all directions(or at least 180°). In an exemplary embodiment of the invention,examination bed 200 is positioned according to the part of patient 180that needs to be examined, for example heart, head or feet. Optionally,the distance along the X coordinate for placing examination bed 200 fromgamma camera system 100 can vary and is limited by the maximal extent ofextendible support arm 140.

FIGS. 2A, 2B, 2C, 2D, 2E and 2F are schematic illustrations of gammacamera system 100, in various positions of use, according to anexemplary embodiment of the invention. In an exemplary embodiment of theinvention, patient 180 is placed on examination bed 200 beside gammacamera system 100. Optionally as shown in FIG. 2A, the detectors of head170 are positioned close to patient 180, wherein one detector detectsevents from a side of the patient and the other detector detects eventsfrom the front (as shown) or back of patient 180. Optionally, extendiblesupport arm 140 begins to extend outward in order for the detectors ofhead 170 to orbit around the upper half of patient 180. In someembodiments of the invention, sensors 160 notify control 190 of gammacamera system 100 of the distance from the patient, so that gamma camerasystem 100 can instruct arm base 130 to rise, and instruct joint 150 torotate head 170 in the XY plane, to reach the position shown in FIG. 2B,without colliding with patient 180. Alternatively or additionally, asystem operator selects a trajectory fitting patient 180, and positionspatient 180 accordingly. In some embodiments of the invention, thetrajectory of head 170 is controlled by the system operator during theexamination.

In an exemplary embodiment of the invention, as shown in FIG. 2C, head170 completes a scan of 180° when head 170 is positioned to measure theopposite upper side of patient 180.

It is noted that vertical movement of the camera heads is not necessaryfor this embodiment of the invention.

Optionally, after scanning 180°, extendible support arm 140 retracts toits original non-extended position. Arm base 130 is lowered so that head170 can pass under patient 180 in order to complete a full trajectory of360° around patient 180. FIGS. 2D, 2E and 2F show head 170 underexamination bed 200, in order to complete the trajectory. It should benoted that FIGS. 2A, 2B, 2C, 2D, 2E and 2F represent intermediatepositions of the full trajectory around patient 180.

In some embodiments of the invention, examination bed 200 comprises athin bed of a material that does not interfere with the radiation.Alternatively, the actual detection is limited to less than 360° fromthe areas not interfered by examination bed 200, for example 210°.Further alternatively, detection is performed only at 180°.

FIGS. 3A, 3B, 3C, 3D and 3E are schematic illustrations of gamma camerasystem 100, in various positions of use, according to an exemplaryembodiment of the invention.

In some embodiments of the invention, joint 150 or extendible supportarm 140 or base 130 allow rotation of head 170 in the YZ plane ofcoordinate system 250 (for example by rotating arm 140 around its axis)to support measuring patient 180 in various postures.

In an exemplary embodiment of the invention, as illustrated in FIG. 3A,patient 180 is positioned standing in front of system 100, at a distancethat is reachable by extendible support arm 140. Alternatively asillustrated in FIG. 3B patient 180 is seated in front of system 100.

Head 170 is rotated 90° in plane YZ in order to be positioned as shownfrom above in FIG. 3C. In an exemplary embodiment of the invention,FIGS. 3C, 3D and 3E, illustrate measuring a 180° contour of patient 180while rotating head 170 in the XZ plane by 90°.

In an exemplary embodiment of the invention, as shown in FIG. 3C, head170 is positioned to encompass a first side of patient 180, that is, itreceives radiation from both the entire front and entire side of thepatient. Extendible support arm 140 expands outward while rotating head170 around joint 150 in the XZ plane to receive radiation from the backof patient 180 as shown in FIG. 3D. Extendible support arm 140 continuesto expand, while the head rotates about pivot 150, until head 170reaches the opposite side as shown in FIG. 3E. Alternatively, the scanis carried out over the front and sides of the patient. Optionally, thescan is carried out over 360°, as described above with respect to FIG.2.

In some embodiments of the invention, gamma camera system 100 can beused to scan the length of patient 180 (for example positioned as inFIG. 3A) by moving arm base 130 up and down along the Y axis ofcoordinate system 250.

While the gamma camera heads are each shown to be as large, in adirection perpendicular to the axis of rotation of the heads, as themaximum extent of the patient, this is not absolutely necessary. Infact, even if the heads are only half this extent, it may possible toacquire radiation from all directions. For example, if the head is halfthe width of the patient (usually the larger dimension of the patientand defining a minimum reconstruction diameter), anterior posteriorradiation from the left side of the patient can be acquired when thecamera heads are in the position shown in FIG. 2F and anterior posteriorradiation from the right side of the patient can be acquired when thecamera heads are in the position shown in FIG. 2D. Similar acquisitionwould apply for other radiation directions. While this would requiremore than 9° degrees of rotation of the heads, it appears that in mostcases 270 degrees would be sufficient, since at least one of thedetectors of head 170 is positioned to scan each of four sides of thepatient. While half the diameter of the reconstruction circle isnecessary, somewhat larger dimensions may be used, such as 60% or up to75% of the diameter of the reconstruction circle, in order to easepositioning and to allow for obese patients.

While this requires a larger angle of scanning, the weight of the headscan be reduced by up to 50%, making the structure both less expensive toproduce and more stable.

In some embodiments of the invention, software is used to analyze thescan results in order to overcome double coverage of areas on thepatient and connect scan results of continuous areas which are scannednon-continuously. In an exemplary embodiment of the invention, softwareeliminates double measurements for example as formed from the scanningunder the patient in FIGS. 2D and 2F. Alternatively or additionally,scan results from overlapping areas are averaged out. Furtheralternatively or additionally, different weights are given to differentscan areas, in order to give preference to scan positions which forexample, are known to give better results.

In some embodiments of the invention, lighter weight solid statedetectors can be used, for example as described in U.S. Pat. No.6,242,745, and/or U.S. Pat. No. 6,621,084 the disclosures of which areincorporated by reference, as well as other solid state detectors asknown in the art, in order to enhance compactness and mobility of system100. In some embodiments system 100 is limited to scanning low energyisotopes, for example as used in cardiology, bones and other diagnosticsin order to allow using heads 170 with less lead shielding and smallerbulk.

In an exemplary embodiment of the invention, the detectors of camerahead 170 may be positioned before scanning, at an angle other than 90°,for example at 80° or at 100° in order to enhance scan results.Optionally, system 100 can automatically control the angle in order toavoid obstacles and enhance scan results during scanning.

In some embodiments of the invention, when system 100 is not in use thedetectors of camera head 170 can be positioned at an angle other than90° in order to allow a more compact parking position. FIGS. 4A, 4B and4C are schematic illustrations of a gamma camera system, in variousparking positions, according to an exemplary embodiment of theinvention.

In FIG. 4A system 100 is shown in a parked position with the detectorsof camera head 170 at 90°. Optionally, one detector of camera head 170can be repositioned to form a 180° angle with the other detector, forexample as shown in FIG. 4B, in order for system 100 to form a smallerfootprint when not in use. Alternatively, the detectors of head 170 canbe rotated and folded back toward column 120 as shown in FIG. 4C inorder to minimize the footprint of the system.

It will be appreciated that the above described methods may be varied inmany ways, including, changing the type of gamma camera used and/ormaterials used in the system. It should also be appreciated that theabove described description of methods and apparatus are to beinterpreted as including apparatus for carrying out the methods andmethods of using the apparatus.

The present invention has been described using non-limiting detaileddescriptions of embodiments thereof that are provided by way of exampleand are not intended to limit the scope of the invention. It should beunderstood that features and/or steps described with respect to oneembodiment may be used with other embodiments and that not allembodiments of the invention have all of the features and/or steps shownin a particular figure or described with respect to one of theembodiments. Variations of embodiments described will occur to personsof the art.

It is noted that some of the above described embodiments may describethe best mode contemplated by the inventors and therefore may includestructure, acts or details of structures and acts that may not beessential to the invention and which are described as examples.Structure and acts described herein are replaceable by equivalents whichperform the same function, even if the structure or acts are different,as known in the art. Therefore, the scope of the invention is limitedonly by the elements and limitations as used in the claims. When used inthe following claims, the terms “comprise”, “include”, “have” and theirconjugates mean “including but not limited to”.

1. A gamma camera system comprising: a pair of gamma camera heads; and astand on which the gamma camera heads are mounted, wherein the camerasystem is configurable in one of at least two configurations, including:an operational condition in which faces of the gamma camera heads forman angle of between 80 and 100 degrees; and a non-operational parkingconfiguration in which a front face of the gamma camera heads form anangle substantially greater than 100 degrees.
 2. A gamma cameraaccording to claim 1 wherein the angle in the non-operating parkingcondition is approximately 180 degrees.
 3. A gamma camera according toclaim 1 wherein the angle in the non-operating parking position issubstantially greater than 180 degrees.
 4. A gamma camera according toclaim 1 wherein in the operating configuration the angle issubstantially equal to 90 degrees.
 5. A gamma camera according to claim1 wherein the gamma camera is a portable camera.
 6. A gamma cameraaccording to claim 1 wherein the camera comprises: a vertical element; asubstantially horizontal arm vertically attached to and verticallymovable with respect to the vertical arm.
 7. A gamma camera according toclaim 6 wherein the substantially horizontal arm is an extendable arm.8. A gamma camera according to claim 7 wherein the extendible arm is atelescopic arm.
 9. A gamma camera according to claim 1 including: anextendible arm on which the pair of cameras heads are mounted, wherein:in the operational condition the arm is extended; and in thenon-operating parking configuration in which the arm is contracted. 10.A gamma camera system comprising: a pair of gamma camera heads connectedto form substantially a right angle; and an extendible arm on which thepair of cameras heads are mounted, wherein the camera system isconfigurable in one of at least two configurations, including: anoperational condition in which the gamma camera heads form substantiallya right angle and the arm is extended; and a non-operational parkingconfiguration in which the arm is contracted.
 11. A gamma camera systemaccording to claim 10 wherein the extendible arm is a telescoping armand the contracted position is a position in which the arm istelescoped.
 12. A gamma camera according to claim 10 wherein the headsform substantially a right angle in the parking configuration.
 13. Agamma camera according to claim 10 wherein the gamma camera heads froman angle substantially greater angle in the non-operating parkingconfiguration than in the operating configuration.
 14. A gamma cameraaccording to claim 13 wherein the angle in the parking condition issubstantially greater than 100 degrees.
 15. A gamma camera according toclaim 12 wherein the gamma cameras head are rotatable about an axissubstantially at the joiner of the two gamma camera heads.
 17. A gammacamera according to claim 11 wherein in the operating configuration theangle is substantially equal to 90 degrees.
 18. A gamma camera accordingto claim 11 wherein the gamma camera is a portable camera.